Standing in the middle of Michigan's Shiawassee National Wildlife Refuge, it’s hard to comprehend the size. It’s about two-thirds the size of Manhattan – some 10,000 acres of marshes and bogs, forest and farm land.
Everywhere you look; there’s a hawk or a heron. Bushes rustle with rodents; and the air is filled with mosquitos.
Here, researchers are tackling invasive cattails -- a common problem in wetlands across the Great Lakes.